# File lib/tapkit/access/adapters/postgresql.rb, line 104
                def add_join( left, right, semantic )
                        clause = assemble_join(left, right, semantic)

                        unless @join_semantic then
                                case semantic
                                when Relationship::INNER_JOIN
                                        @join_semantic = "INNER"
                                when Relationship::FULL_OUTER_JOIN
                                        @join_semantic = "FULL OUTER"
                                when Relationship::LEFT_OUTER_JOIN
                                        @join_semantic = "LEFT OUTER"
                                when Relationship::RIGHT_OUTER_JOIN
                                        @join_semantic = "RIGHT OUTER"
                                end
                        end

                        @join_on << clause
                        clause
                end